Many surgical procedures require vessels or other tissues of the human body to be ligated during the surgical process. For example, many surgical procedures require cutting blood vessels (e.g., veins or arteries), and these blood vessels may require ligation to reduce bleeding. In some instances, a surgeon may wish to ligate the vessel temporarily to reduce blood flow to the surgical site during the surgical procedure. In other instances a surgeon may wish to permanently ligate a vessel. Ligation of vessels or other tissues can be performed by closing the vessel with a ligating clip, or by suturing the vessel with surgical thread. The use of surgical thread for ligation requires complex manipulations of the needle and suture material to form the knots required to secure the vessel. Such complex manipulations are time-consuming and difficult to perform, particularly in endoscopic surgical procedures, which are characterized by limited space and visibility. By contrast, ligating clips are relatively easy and quick to apply. Accordingly, the use of ligating clips in endoscopic as well as open surgical procedures has grown dramatically.
Various types of hemostatic and aneurysm clips are used in surgery for ligating blood vessels or other tissues to stop the flow of blood. Such clips have also been used for interrupting or occluding ducts and vessels in particular surgeries such as sterilization procedures. Typically, a clip is applied to the vessel or other tissue by using a dedicated mechanical instrument commonly referred to as a surgical clip applier, ligating clip applier, or hemostatic clip applier. Generally, the clip is left in place after application to the tissue until hemostasis or occlusion occurs.
Ligating clips can be classified according to their geometric configuration (e.g., symmetric clips or asymmetric clips), and according to the material from which they are manufactured (e.g., metal clips or polymeric clips). Symmetric clips are generally “U” or “V” shaped and thus are substantially symmetrical about a central, longitudinal axis extending between the legs of the clip. Symmetric clips are usually constructed from metals such as stainless steel, titanium, tantalum, or alloys thereof. But, with the advent of high technology diagnostic techniques using computer tomography (CATSCAN) and magnetic resonance imaging (MRI), metallic clips have been found to interfere with the imaging techniques. To overcome such interference limitations, biocompatible polymers have been increasingly used for surgical clips.
Some well known polymeric clips are disclosed in U.S. Pat. No. 4,834,096 to Oh et al. and U.S. Pat. No. 5,062,846 to Oh et al., both of which are commonly owned with the assignee of the present invention, the disclosures of which are herein incorporated by reference in their entirety. These plastic clips generally comprise a pair of curved legs joined at their proximal ends with an integral hinge or heel.
Although plastic ligating clips are well known in the surgical area and improvements have been made to the ligating clips, including providing protrusions on the inner surfaces of the leg members to impede the lateral movement of a vessel during clip closure (see, for example, the aforementioned U.S. Pat. Nos. 4,834,096 and 5,062,846), these improvements have been less effective in preventing movement of the clip along the length of a vessel or tissue during and after clip closure. One potential improvement in this area is disclosed in commonly-owned U.S. Patent Application Pub. No. 2005/0165423 A1 by Gallagher et al., the disclosure of which is incorporated by reference in its entirety, which discloses a polymeric surgical clip having an interlocking tongue-in-groove mechanism formed by a lip or tongue protruding from a portion of the inner surface of one leg and a groove formed in a corresponding portion of the inner surface of the other leg; or a lock-step mechanism, formed by complementary L-shaped notches wherein a notch is provided in a portion of the inner surface of each leg. The interlocking mechanisms act to impede movement of the clip relative to the vessel being clamped.
In all of the known ligating clips however, there remains a need to improve the effectiveness of clamping about a vessel, while minimizing the damage to the vessel and surrounding tissue. The occlusion of the vessel by a ligating clip can accidentally damage the vessel or severe it. Therefore, a ligating clip must have a sufficient degree of clamping force and retention on a vessel, so as not to move relative to the vessel when applied, while also preserving tissue integrity and minimizing damage. Accordingly, there is a need to provide an improved surgical ligating clip with that serves to secure the tissue or vessel engaged by the clip, while robustly remaining attached to the vessel with a minimum level of damage to tissue.